(Adds opinion from conservative justices, case background)
By Andrew Chung
Oct 28 (Reuters) - The U.S. Supreme Court on Wednesday handed a setback to Republicans by declining to quickly decide whether to hear their latest bid to overturn a lower court's ruling that extended Pennsylvania's deadline to receive mail-in ballots in next Tuesday's election.
The justices declined to expedite their consideration of the request by the Republican Party of Pennsylvania to hear and decide before the election its appeal of a ruling by the state's top court ordering officials to count mail-in ballots that are postmarked by Election Day and received up to three days later.
The Supreme Court already rejected a Republican request to block the lower court ruling on Oct. 19.
Pennsylvania is an election battleground state crucial to Trump's re-election chances against Democrat Joe Biden. Trump won Pennsylvania in 2016 but is trailing Biden in many opinion polls in the state ahead of Election Day.
Newly appointed Justice Amy Coney Barrett did not participate in Wednesday's decision. Barrett, who joined the court on Tuesday, did not have time to fully review the case filings, a court spokeswoman said in a statement.
Justice Samuel Alito, joined by fellow conservative Justices Clarence Thomas and Neil Gorsuch, said in a written opinion that it would be "highly desirable" to review the state court's ruling before the election.
"But I reluctantly conclude that there is simply not enough time at this late date to decide the question before the election," Alito wrote.
Trump's fellow Republicans in many states have opposed measures to facilitate voting during the coronavirus pandemic. The public health crisis has prompted an increase in requests for mail-in ballots as voters seek to avoid crowds at polling places.
In the earlier decision, the court, shorthanded after the death of Justice Ruth Bader Ginsburg, was divided 4-4, leaving in place a Pennsylvania Supreme Court ruling in favor of state Democrats to extend the deadline. Chief Justice John Roberts joined the three liberal justices in that earlier decision in denying the request, but the four other conservative justices said they would have sided with Republicans to block the extension. (Reporting by Andrew Chung; Additional reporting by Lawrence Hurley. Editing by Will Dunham)